But Zaid has told the BBC - which will show a special Panorama documentary about the killings tomorrow - that he had nothing to do with the murders, and claimed police are "covering up" the gunman's real intended target.

French prosecutors suspect the two brothers had fallen out in a dispute over inheritance, but Zaid rejected these claims, calling the accusations about his connection to the killings "ridiculous". He also said he would be willing to take a lie detector test.

He described his relationship with Saad as "very brotherly and close" even though they had only communicated through their lawyers in the 11 months before Saad's death.

And he claimed French police had not investigated the murder of cyclist Sylvain Mollier thoroughly enough.

He claimed: "They are covering up for someone in France in that region and they know it.

"Sylvain Mollier was involved in family disputes and was an outsider to [his] rich family. There is something more to it locally... most crime has local roots."